Ok, so I bought the car about 3 weeks ago, and I knew it didn't pass for MA emissions when I bought it (took it in on trade...I'm the sales manager for a Chrysler/Dodge/Jeep dealer). Brought it through for a sticker, found out it barely failed for NOx. The MA limit for a '91 is 2.50 (whatever the hell it is...PPM???) for NOx, and it blew a 2.65. Not bad, right? So I bring it to my uncle (an excellent mechanic, not a backyard idiot), and he discovers the EGR solenoid isn't working. So I get that, among other things...new EGR valve, plugs, wires, cap, rotor, PCV valve, O2 sensor, even a fuel filter.

What happens? Now the car blew a 2.60!!! It barely changed!!!! The HC and CO are way below the limit, but NOx is still off. I have 2 remaining solutions...

1) Replace the Hypercrap Stage 2 in it with the original chip (the former owner gave it to me). Has anyone ever changed back to an OEM chip and seen a measurable drop in emissions?

2) Replace a 3 year old "high flow" cat the previous owner put on.

Is there anything I'm missing? Help! Other than a fan switch that doesn't turn on when hot (fan only turns on when the A/C is engaged), it runs beautiful...

ARGH...any help is appreciated.

 

NOX is created by cylinder temp. You need to get the temp lower. Timing curve too high, Coolant temp too low, EGR passage plugged/not working, lean condition..etc, etc. I would imagine you test with a dyno, since NOX is being tested. Any reading with a "." in it would be "%". Reading with just numbers would be "PPM"..... example: 2.2% CO. 312 PPM HC.

 

just a suggestion...


reset the computer, by unplugging the battery... then 20 min later re-connect the battery start the engine , let it idle for 5 min.. then turn it off..

10 min later, turn it on, and let it idle again for 5 min....

ALSO

What kind of gasoline is in the tank?
fill it up with 93 octane... its a cleaner burning gas...(and hotter, but not a bad thing.. the hotter it is.. the more efficient it is burned) not exactly going to make the Engine Block Hotter... thats from friction, not the temp of gas being ignited.... anywayz (the more gas/air) mixture ignited, the lower the emisions should be..

Take it out for a long drive... get everything working and functioning great..

Then after the LONGGG drive... Reset the computer ---again... and follow the steps above... After a long drive, on great gas, new spark plugs wires dist and rotor... aswell as them other parts... IM sure something is bound to change, and hopefully that would fix your problem, just enough to pass the emmisions

u should be good to go....
Retake the test............
Im thinking this because....

You made some minor changes and lowered your reading by .05

Now your gonna make some more changes and they also might help you get an even more lower rating...

hope you pass man

 

i was just reading through my chiltons, and i had an idea when i came across the section on NOx...

i was thinking Maybe your spark plugs are sparking too long, and too high of a voltage.... like if you had some "premium" plugs

Which then i thought, you should have OEM spark plugs, and.... then i was thinking, if you were to use 87 octane, i wonder if that would burn cooler than a higher octane gas which would burn hotter. contridicting what i may have said earlier

I think you should look into the EGR Valve again, to see if something isnt functioning as specified, because i read.. the EGR valve is controlled by Vacuum, which opens and close's in response to the vacuum signals to admit exhaust gases into the fuel/air mixture. The exhaust gases lower peak combustion tempatures, ---Reducing the Formation of NOx--- as 1991L98G92 said...

im no expert.. but from reading that, i can recomend double checking all the vacuum hose's etc.. and also.. my brother told me to clean to clean my actual valve and around it... apparently, there is lotsof carbon build up...

also.. take it a step further in the chain of reactions and find out whats making the vacuum pressure etc... and then a step forward...

But i'd say if your car runs great and stuff when you drive it... its just producing a high amount of NOx... this might be the solution... keep in mind i know you already replaced the egr valve and the solenoid ..

good luck - chris

 

Well, I was also thinking, should I just take the damn Hypertech chip out of the car? I too read that ignition timing plays a roll in NOx...now, I know the Hypertech is supposedly only supposed to change WOT settings, but I watched the tech drive it on the dyno here at work yesterday, and he was goosing it good in gear to get it to speed...possibly triggering the WOT settings?

To answer some questions raised here...

1) My uncle said he checked all the vaccum hoses going into the EGR valve, and all were fine.
2) I have been using nothing but Mobil 93 octane, trying to get things cleaned up in it.
3) I can try to reset the computer as recommended...it can't hurt. I thought unplugging the battery for a minute or two was the same as the recommended 20 minutes though? I will say one thing...I've put 1,000 miles on it in 3 weeks by originally using it as my demo here for work, deciding if I wanted to buy it or not (I knew all along I did )...my daily commute is 100 miles of nothing but freeway driving, so everything gets nice and heated up/blown out on the highway.
4) For the hell of it, I threw some of that "Guaranteed to Pass" stuff in the tank last night, with the hope that it might clean up the cat a little.

I can look at the vaccum hoses, but to be honest, I'm not exactly the greatest mechanic in the world. If my uncle claims everything was fine with them, I'd tend to defer to his judgement on them. I guess at this point, resetting the computer, changing the chip and running that Guaranteed to Pass through it for a tank isn't a bad plan of attack? I'm so friggen close, its not even funny...but this is my first car to never pass for a sticker, and its irritating the crap out of me that something isn't running right.

I can try putting 87 in it after the chip change as well...I'd love to hear a second opinion on that. Thanks to anyone who can help!
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One last thing...my uncle showed me a wire that can be disconnected...it runs near the RF strut tower. Supposedly, its a wire that you disconnect to reset the timing? It triggers the SES light, but supposedly sets the timing back to base timing and would clean the emissions up further.

Would this have the same affect as taking out the chip, or does the chip have an affect above and beyond what unplugging this wire does?

 

i dont know what that chip does..

Every chip is designed to do different stuff.. however i do recommend putting in the computer chip which is OEM, because a chip which is going to "spice things up" might be like eating mexican food before a hot date... basically ****., in regards to passing MA's test ... i recommend using OEM only.. u dont need any extra stuff to give u more HP when ur taking a test.. would you do cocaine before work?

and the 87 octane gas theory might prove some serious results...

tommorow im gonna take apart my EGR system on my TPI....

what size engine and type of injection was your car.. i have my chiltons right here.. i can try to figure out some ****..


One last thing...my uncle showed me a wire that can be disconnected...it runs near the RF strut tower. Supposedly, its a wire that you disconnect to reset the timing? It triggers the SES light, but supposedly sets the timing back to base timing and would clean the emissions up further

tell me more about that wire you can disconnect.... and what is its purpouse?

 

Its a 305 with throttle body injection.

All that I know about the wire is that its on the RH side of the engine bay near the strut tower, and that disconnecting it will bring on the SES light, the idle changes slightly, and it supposedly brings the timing back to base timing (he claimed stock timing is 10 degrees advanced?). I mean, if advanced timing makes NOx higher, retarding it sure makes sense to me!

 

hrm i dont think that would apply to me i have 350 tpi , 2 diff setups

 

fresh tune up parts, oil change, tank of premium gas with a gallon of Colemans Lantern fluid. Its a recipe for a guy I know with a big block camaro in canada and he always passes.

 

Other than the Lantern fluid, I already have all that...

I think I'm safer with Guaranteed to Pass than I am lantern fluid
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Where did the lantern fluid idea come from?

 

i didn't notice if this was said or not.
with the motor at idle, reach under the EGR valve & lift up on the diaphragm, it should make the motor start running ruff or maybe even die, if there is no change in how the motor runs pull the EGR valve & clean the passages.

also, putting the stock chip back in would be a good ideal

 

The hyperchip could advance the timing and delete the EGR function. NOX is created above 2500 degrees F. Advanced timing causes higher temps. The wire for the timing should be tan with a black stripe. Disconnecting will cause the computer to go into base mode and cause the fuel system to go full rich. So disconnecting it and driving will not help in "cleaning" anything. If your timing is 10 degrees advanced from spec, it will cause a higher HC and NOX readings. Is timing checked at the inspection?

 

Timing is not checked, and it will not matter that the SES light is on...hence the idea he had. The idea was not to drive it and "clean it" out, but to pull it solely for the emissions test...with his thought being that the retarded timing would create less emissions.

I thought 10 degrees advanced WAS the spec for a 305 TBI the way he was talking? I must have misunderstood.

I think I just need to pull the Hypertech out and finish running the stuff in the tank through it, then try it for the 3rd time. If it fails, then I'll change out the no-name, 2-3 year old high flow cat it has. If it STILL fails after that? I'm applying for a waiver of emissions because I'll have spent so much $$ trying to make it pass, the state of MA will waive my emissions requirements.

The problem is, it will STILL **** me off that something is not right!

 

^^^ Sorry, this is a double post...I didn't realize I was signed in under my friend's account on his computer

Timing is not checked, and it will not matter that the SES light is on...hence the idea he had. The idea was not to drive it and "clean it" out, but to pull it solely for the emissions test...with his thought being that the retarded timing would create less emissions.

I thought 10 degrees advanced WAS the spec for a 305 TBI the way he was talking? I must have misunderstood.

I think I just need to pull the Hypertech out and finish running the stuff in the tank through it, then try it for the 3rd time. If it fails, then I'll change out the no-name, 2-3 year old high flow cat it has. If it STILL fails after that? I'm applying for a waiver of emissions because I'll have spent so much $$ trying to make it pass, the state of MA will waive my emissions requirements.

The problem is, it will STILL **** me off that something is not right!

 

Not sure where he heard it, but it has something to do with making the car run much cleaner while the lantern fluid is in wih the gas.

 

The Hypertech chip advances the timing, which will make the cylinder temps higher. Change back to the original chip, run Lucas Oil fuel injector cleaner through it, keep running 93 octane. Wait about a week and you should have a grin and a sticker. Then put the Hypertech chip back in.

 

The timing on a 305 TBI should be 0 degrees (TDC). 6 degrees for a Carbed motor and TPI.

 

My '90 Formula failed for the second time today because of high NOx too. I just installed a new full exhaust as well as new plugs and wires. Is there any resolution?

 

Wait, your stock timing is 10* advanced with the timign wire disconnected? If so, you've found the problem- over-advanced timing. Almost guaranteed. Stock spec is 0* with timing wire disconnected. Most can easily get away with it bumped up to 4* advanced, but that's about it. At 10* initial you're almost certainly spiking the comubstion temps and pushing the NOx over the limit.

Given that you're passing on everything else with flying colors and just barely missing on the NOx I'm gonna give you about 80% probability that's your problem.

 

don't think its the chip because the stage 2 chip is 50 state legal. also using a higher octane fuel usually help reduce HOx readings, because it burns faster which reduces combustion temps. the octane rating refers to the fuel's volatility. I would check base timing, egr system, O2 sensor, also pull a plug and see it you have a lot of carbon build up on the pistons, and of course the last thing you check is the CAT.

 

i totally agree with damon, setting your base timing back to stock which i think is 0 for tbi is mandatory for reducing the nox, also try adding some 90% isopropyl alcohol in your gas.

 

Just to add what has already been mentioned.

I would put the stock chip back in (off the shelf chips add fuel and timing where it is often not needed) and set the timing back to 0°. The stock LO3 heads (187 swirl ports) are fast burn heads and do not need a lot of ignition advance. Similarly, they do not need high octane fuel. If your engine is fairly clean (not a 350k carbon monster) you should be able to run 87 octane all day long in any driving condition. TBI motors with slight carbon buildup may require 89. None the less, 90+ is too much for a stock motor running SP heads. TBI motors with SP heads will make less power than the stock rating if the initial advance is too high combined with overly aggressive octanes.

 

From a "backyard idiot"!!! Try runing the car down to 1/4 tank and add 5 gals of Methanol..... am told that will practically get any car through emissions..... but then ... I am one of those back yard idiots that races a 600 HP Chevy Nova..... chuckles.....

 

Not sure if anyone needed it still.....but this is what resets the timing.

https://www.thirdgen.org/forums/atta...p-dsc03788.jpg

By the RF Stut Tower....INSIDE wire loom.
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Im going to try that....the methanol. But where do I buy it? And how much.

Should I run down to 1/4...then add 5 gals....then fill the rest up with gas? Or take the test with the 1/4 tank and 5gals of meth.

P.S. I dont do METH unless it helps my car.

 

Just Bill says use Methanol....whats the diff? Is one better than the other at cleaning. Which is cheaper for cost?

 

Haha, I have not heard of lantern fluid before, thats cool!

Most common is Shellac thinner.

AKA, Denatured Pure Alcohol..
Usually used for high HC numbers.. but, it might work

 

I use that at work all the time....boutta score some and hopefully it helps me pass when I need to.